Hydrocarbon conversion with an acidic multimetallic catalytic composite

ABSTRACT

Hydrocarbons are converted by contacting them at hydrocarbon conversion conditions with an acidic multimetallic catalytic composite comprising a combination of catalytically effective amounts of a platinum group component, a lanthanide series component, a nickel component, and a halogen component with a porous carrier material. The platinum group, lanthanide series, nickel, and halogen components are present in the multimetallic catalyst in amounts respctively, calculated on an elemental basis, corresponding to about 0.01 to about 2 wt.% platinum group metal, about 0.01 to about 5 wt.% lanthanide series metal, about 0.05 to about 5 wt.% nickel, and about 0.1 to about 3.5 wt.% halogen. Moreover, these metallic components are uniformly dispersed throughout the porous carrier material in carefully controlled oxidation states such that substantially all of the platinum group metal is present therein in the elemental metallic state, substantially all of the catalytically available nickel component is present in the elemental metallic state or in a state which is reducible to the elemental metallic state under hydrocarbon conversion conditions, or in a mixture of these states, while substantially all of the lanthanide series component is present in an oxidation state above that of the elemental metal. A specific example of the type of hydrocarbn conversion process disclosed is a process for the catalytic reforming of a low-octane gasoline fraction wherein the gasoline fraction and a hydrogen stream are contacted with the acidic multimetllic catalyst disclosed herein at reforming conditions.

The subject of the present invention is a novel acidic multi-metalliccatalytic composite which has exceptional activity and resistance todeactivation when employed in a hydrocarbon conversion process thatrequires a catalyst having both a hydrogenation-dehydrogenation functionand a carbonium ion-forming function. More precisely, the presentinvention involves a novel dual-function acidic multimetallic catalyticcomposite which, quite surprisingly, enables substantial improvements inhydrocarbon conversion processes that have traditionally used adual-function catalyst. In another aspect, the present inventioncomprehends the improved processes that are produced by the use of acatalytic composite comprising a combination of catalytically effectiveamounts of a platinum group component a nickel component, a lanthanideseries component, and a halogen component with a porous carriermaterial; specifically, an improved reforming process which utilizes thesubject catalyst to improve activity, selectivity, and stabilitycharacteristics.

Composites having a hydrogenation-dehydrogenation function and acarbonium ion-forming function are widely used today as catalysts inmany industries, such as the petroleum and petrochemical industry, toaccelerate a wide spectrum of hydrocarbon conversion reactions.Generally, the carbonium ion-forming function is thought to beassociated with an acid-acting material of the porous, adsorptive,refractory oxide type which is typically utilized as the support orcarrier for a heavy metal component such as the metals or compounds ofmetals of Groups V through VIII of the Periodic Table to which aregenerally attributed the hydrogenation-dehydrogenation function.

These catalytic composites are used to accelerate a wide variety ofhydrocarbon conversion reactions such as hydrocracking, hydrogenolysis,isomerization, dehydrogenation, hydrogenation, desulfurization,cyclization, polymerization, alkylation, cracking, hydroisomerization,dealkylation, transalkylation, etc. In many cases, the commercialapplications of these catalysts are in processes where more than one ofthe reactions are proceeding simultaneously. An example of this type ofprocess is reforming wherein a hydrocarbon feedstream containingparaffins and naphthenes is subjected to conditions which promotedehydrogenation of naphthenes to aromatics, dehydrocyclization ofparaffins to aromatics, isomerization of paraffins and naphthenes,hydrocracking and hydrogenolysis of naphthenes and paraffins, and thelike reactions, to produce an octane-rich or aromatic-rich productstream. Another example is a hydrocracking process wherein catalysts ofthis type are utilized to effect selective hydrogenation and cracking ofhigh molecular weight unsaturated materials, selective hydrocracking ofhigh molecular weight materials, and other like reactions, to produce agenerally lower boiling, more valuable output stream. Yet anotherexample is a hydroisomerization process wherein a hydrocarbon fractionwhich is relatively rich in straight-chain paraffin compounds iscontacted with a dual-function catalyst to produce an output stream richin isoparaffin compounds.

Regardless of the reaction involved or the particular process involved,it is of critical importance that the dual-function catalyst exhibit notonly the capability to initially perform its specified functions, butalso that it has the capability to perform them satisfactorily forprolonged periods of time. The analytical terms used in the art tomeasure how well a particular catalyst performs its intended functionsin a particular hydrocarbon reaction environment are activity,selectively, and stability. And for purposes of discussion here, theseterms are conveniently defined for a given charge stock as follows: (1)activity is a measure of the catalyst's ability to convert hydrocarbonreactants into products at a specified severity level where severitylevel means the conditions used--that is, the temperature, pressure,contact time and presence of diluents such as H₂ ; (2) selectivityrefers to the amount of desired product or products obtained relative tothe amount of reactants charged or converted; (3) stability refers tothe rate of change with time of the activity and selectivityparameters--obviously, the smaller rate implying the more stablecatalyst. In a reforming process, for example, activity commonly refersto the amount of conversion that takes place for a given charge stock ata specified severity level and is typically measured by octane number ofthe C₅ + product stream; selectivity refers to the amount of C₅ + yield,relative to the amount of the charge, that is obtained at the particularactivity or severity level; and stability is typically equated to therate of change with time of activity, as measured by octane number ofC₅ + product, and of selectivity as measured by C₅ + yield. Actually,the last statement is not strictly correct because generally acontinuous reforming process in run to produce a constant octane C₅ +product with severity level being continuously adjusted to attain thisresult; and furthermore, the severity level is for this process usuallyvaried by adjusting the conversion temperature in the reaction so that,in point of fact, the rate of change of activity finds response in therate of change of conversion temperature and changes in this lastparameter are customarily taken as indicative of activity stability.

As is well known to those skilled in the art, the principal cause ofobserved deactivation or instability of a dual-function catalyst when itis used in a hydrocarbon conversion reaction is associated with the factthat coke forms on the surface of the catalyst during the course of thereaction. More specifically, in these hydrocarbon conversion processes,the conditions utilized typically result in the formation of heavy, highmolecular weight, black, solid or semi-solid, carbonaceous materialwhich is a hydrogen-deficient polymeric substance having properties akinto both polynuclear aromatics and graphite. This material coats thesurface of the catalyst and thus reduces its activity by shielding itsactive sites from the reactants. In other words, the performance of thisdual-function catalyst is sensitive to the presence of carbonaceousdeposits or coke on the surface of the catalyst. Accordingly, the majorproblem facing workers in this area of the art is the development ofmore active and/or selective catalytic composites that are not assensitive to the presence of these carbonaceous materials and/or havethe capability to suppress the rate of the formation of thesecarbonaceous materials on the catalyst. Viewed in terms of performanceparameters, the problem is to develop a dual-function catalyst havingsuperior activity, selectivity, and stability characteristics. Inparticular, for a reforming process the problem is typically expressedin terms of shifting and stabilizing the C₅ + yield-octane relationshipat the lowest possible severity level--C₅ + yield being representativeof selectivity and octane being proportional to activity.

I have now found a dual-function acidic multimetallic catalyticcomposite which possesses improved activity, selectivity, and stabilitycharacteristics when it is employed in a process for the conversion ofhydrocarbons of the type which have heretofore utilized dual-functionacidic catalytic composites such as processes for isomerization,hydroisomerization, dehydrogenation, desulfurization, denitrogenization,hydrogenation, alkylation, dealkylation, disproportionation,polymerization, hydrodealkylation, transalkylation, cyclization,dehydrocyclization, cracking, hydrocracking, halogenation, reforming,and the like processes. In particular, I have ascertained that an acidiccatalyst, comprising a combination of catalytically effective amounts ofa platinum group component a nickel component, a lanthanide seriescomponent, and a halogen component with a porous refractory carriermaterial, can enable the performance of hydrocarbon conversion processesutilizing dual-function catalysts to be substantially improved if themetallic components are uniformly dispersed throughout the carriermaterial and if their oxidation states are controlled to be in thestates hereinafter specified. Moreover, I have determined that an acidiccatalytic composite, comprising a combination of catalytically effectiveamounts of a platinum group component, a nickel component, a lanthanideseries component, and a halogen component with an alumina carriermaterial, can be utilized to substantially improve the performance of areforming process which operates on a low-octane gasoline fraction toproduce a high-octane reformate if the metallic components are uniformlydispersed throughout the alumina carrier material, if the catalyst isprepared and maintained during use in the process in a substantiallysulfur-free state, and if the oxidation states of the metalliccomponents are fixed in the state hereinafter specified. In the case ofa reforming process, the principal advantage associated with the use ofthe present invention involves the acquisition of the capability tooperate in a stable manner in a high severity operation; for example, alow or moderate pressure reforming process designed to produce a C₅ +reformate having an octane of about 100 F-1 clear. As indicated, thepresent invention essentially involves the finding that the addition ofa combination of a lanthanide series component and a nickel component toa dual-function acidic hydrocarbon conversion catalyst containing aplatinum group component can enable the performance characteristics ofthe catalyst to be sharply and materially improved, if the hereinafterspecified limitations on amounts of ingredients, control of sulfur,oxidation states of metallic ingredients, and distribution of metalliccomponents in the support are met.

It is, accordingly, one object of the present invention to provide anacidic multimetallic hydrocarbon conversion catalyst having superiorperformance characteristics when utilized in a hydrocarbon conversionprocess. A second object is to provide an acidic multimetallic catalysthaving dual-function hydrocarbon conversion performance characteristicsthat are relatively insensitive to the deposition of hydrocarbonaceousmaterial thereon. A third object is to provide preferred methods ofpreparation of this acidic multimetallic catalytic composite whichinsures the achievement and maintenance of its properties. Anotherobject is to provide an improved reforming catalyst having superioractivity, selectivity, and stability characteristics. Yet another objectis to provide a dual-function hydrocarbon conversion catalyst whichutilizes a combination of a lanthanide series component and a nickelcomponent to beneficially interact with, selectively promote andstabilize an acidic catalyst containing a platinum group component.

In brief summary, the present invention is, in one embodiment, an acidiccatalytic composite comprising a porous carrier material containing, onan elemental basis, about 0.01 to about 2 wt. % platinum group metal,about 0.05 to about 5 wt. % nickel, about 0.01 to about 5 wt. %lanthanide series metal, and about 0.1 to about 3.5 wt. % halogen;wherein the platinum group metal, lanthanide series metal, andcatalytically available nickel are uniformly dispersed throughout theporous carrier material; wherein substantially all of the platinum groupmetal is present in the elemental metallic state; wherein substantiallyall of the lanthanide series metal is preferably in an oxidation stateabove that of the elemental metal; and wherein substantially all of thecatalytically available nickel is present in the elemental metallicstate or in a state which is reducible to the elemental metallic stateunder hydrocarbon conversion conditions or in a mixture of these states.

A second embodiment relates to an acidic catalytic composite comprisinga porous carrier material containing, on an elemental basis, about 0.05to about 1 wt. % platinum group metal, about 0.1 to about 2.5 wt. %nickel, about 0.05 to about 2 wt. % lanthanide series metal, and about0.5 to about 1.5 wt. % halogen; whereiin the platinum group metal,lanthanide series metal, and catalytically available nickel areuniformly dispersed throughout the porous carrier material; whereinsubstantially all of the platinum group metal is present in thecorresponding elemental metallic state; wherein substantially all of thelanthanide series metal is present in an oxidation state above that ofthe elemental metal; and wherein substantially all of the catalyticallyavailable nickel is present in the elemental metallic state or in astate which is reducible to the elemental metallic state underhydrocarbon conversion conditions or in a mixture of these states.

A third embodiment relates to the catalytic composite described in thefirst or second embodiment wherein the halogen is combined chloride.

Yet another embodiment involves a process for the conversion of ahydrocarbon comprising contacting the hydrocarbon and hydrogen with thecatalytic composite described above in the first or second or thirdembodiment at hydrocarbon conversion conditions.

A preferred embodiment comprehends a process for reforming a gasolinefraction which comprises contacting the gasoline fraction and hydrogenwith the catalytic composite described above in the first or second orthird embodiment at reforming conditions selected to produce a highoctane reformate.

A highly preferred embodiment is a process for reforming a gasolinefraction which comprises contacting the gasoline fraction and hydrogenin a substantially water-free and sulfur-free environment with thecatalytic composite characterized in the first, second, or thirdembodiment at reforming conditions selected to produce a high octanereformate.

Other objects and embodiments of the present invention relate toadditional details regarding preferred catalytic ingredients, preferredamounts of ingredients, suitable methods of composite preparation,operating conditions for use in the hydrocarbon conversion processes,and the like particulars, which are hereinafter given in the followingdetailed discussion of each of these facets of the present invention.

The acidic multimetallic catalyst of the present invention comprises aporous carrier material or support having combined therewithcatalytically effective amounts of a platinum group component, a nickelcomponent, a lanthanide series component, and a halogen component.

Considering first the porous carrier material utilized in the presentinvention, it is preferred that the material be a porous, adsorptive,high-surface area support having a surface area of about 25 to about 500m² /g. The porous carrier material should be relatively refractory tothe conditions utilized in the hydrocarbon conversion process, and it isintended to include within the scope of the present invention carriermaterials which have traditionally been utilized in dual-functionhydrocarbon conversion catalysts such as: (1) activated carbon, coke, orcharcoal; (2) silica or silica gel, silicon carbide, clays, andsilicates including those synthetically prepared and naturallyoccurring, which may or may not be acid treated, for example, attapulgusclay, china clay, diatomaceous earth, fuller's earth, kaolin,kieselguhr, etc., (3) ceramics, porcelain, crushed firebrick, bauxite;(4) refractory inorganic oxides such as alumina, titanium dioxide,zirconium dioxide, chromium oxide, beryllium oxide, vanadium oxide,cesium oxide, hafnium oxide, zinc oxide, magnesia, boria, thoria,silica-alumina, silica-magnesia, chromia-alumina, alumina-boria,silica-zirconia, etc; (5) crystalline zeolitic aluminosilicates such asnaturally occurring or synthetically prepared mordenite and/orfaujasite, either in the hydrogen form or in a form which has beentreated with multivalent cations; (6) spinels such as MgAl₂ O₄, FeAl₂O₄, ZnAl₂ O₄, MnAl₂ O₄, CaAl₂ O₄, and other like compounds having theformula MO.Al₂ O₃ where M is a metal having a valence of 2; and (7)combinations of elements from one or more of these groups. The preferredporous carrier materials for use in the present invention are refractoryinorganic oxides, with best results obtained with an alumina carriermaterial. Suitable alumina materials are the crystalline aluminas knownas gamma-, eta-, and theta-alumina, with gamma- or eta-alumina givingbest results. In addition, in some embodiments the alumina carriermaterial may contain minor proportions of other well known refractoryinorganic oxides such as silica, zirconia, magnesia, etc.; however, thepreferred support is substantially pure gamma- or eta-alumina. Preferredcarrier materials have an apparent bulk density of about 0.3 to about0.8 g/cc and surface area characteristics such that the average porediameter is about 20 to 300 Angstroms, the pore volume is about 0.1 toabout 1 cc/g and the surface area is about 100 to about 500 m² /g. Ingeneral, best results are typically obtained with a gamma-aluminacarrier material which is used in the form of spherical particleshaving: a relatively small diameter (i.e. typically about 1/16 inch), anapparent bulk density of about 0.3 to about 0.8 g/cc, a pore volume ofabout 0.4 ml/g, and a surface area of about 150 to about 250 m² /g.

The preferred alumina carrier material may be prepared in any suitablemanner and may be synthetically prepared or natural occurring. Whatevertype of alumina is employed, it may be activated prior to use by one ormore treatments including drying, calcination, steaming, etc., and itmay be in a form known as activated alumina, activated alumina ofcommerce, porous alumina, alumina gel, etc. For example, the aluminacarrier may be prepared by adding a suitable alkaline reagent, such asammonium hydroxide, to a salt of aluminum such as aluminum chloride,aluminum nitrate, etc., in an amount to form an aluminum hydroxide gelwhich upon drying and calcining is converted to alumina. The aluminacarrier may be formed in any desired shape such as spheres, pills,cakes, extrudates, powders, granules, tablets, etc., and utilized in anydesired size. For the purpose of the present invention a particularlypreferred form of alumina is the sphere; and alumina spheres may becontinuously manufactured by the well-known oil drop method whichcomprises: forming an alumina hydrosol by any of the techniques taughtin the art and preferably by reacting aluminum metal with hydrochloricacid, combining the resultant hydrosol with a suitable gelling agent anddropping the resultant mixture into an oil bath maintained at elevatedtemperatures. The droplets of the mixture remain in the oil bath untilthey set and form hydrogel spheres. The spheres are then continuouslywithdrawn from the oil bath and typically subjected to specific agingtreatments in oil and an ammoniacal solution to further improve theirphysical characteristics. The resulting aged and gelled particles arethen washed and dried at a relatively low temperature of about 300° F.to about 400° F. and subjected to a calcination procedure at atemperature of about 850° F. to about 1300° F. for a period of about 1to about 20 hours. This treatment effects conversion of the aluminahydrogel to the corresponding crystalline gamma-alumina. See theteachings of U.S. Pat. No. 2,620,314 for additional details.

Another particularly preferred alumina carrier material is synthesizedfrom a unique crystalline alumina powder which has been characterized inU.S. Pat. Nos. 3,852,190 and 4,012,313 as a byproduct from a Zieglerhigher alcohol synthesis reaction as described in Ziegler's U.S. Pat.No. 2,892,858. For purposes of simplification, the name "Ziegleralumina" is used herein to identify this material. It is presentlyavailable from the Conoco Chemical Division of Continental Oil Companyunder the trademark Catapal. This material is an extremely high purityalpha-alumina monohydrate (boehmite) which after calcination at a hightemperature has been shown to yield a high purity gamma-alumina. It iscommercially available in three forms: (1) Catapal SB--a spray driedpowder having a typical surface area of 250 m² /g; (2) Catapal NG--arotary kiln dried alumina having a typical surface area of 180 m² /g;and (3) Dispal M--a finely devided dispersable product having a typicalsurface area of about 185 m² /g. For purposes of the present invention,the preferred starting material is the spray dried powder, Catapal SB.This alpha-alumina monohydrate powder may be formed into a suitablecatalyst material according to any of the techniques known to thoseskilled in the catalyst carrier material forming art. Spherical carriermaterial particles can be formed, for example, from this Ziegler aluminaby: (1) converting the alpha-alumina monohydrate powder into an aluminasol by reaction with a suitable peptizing acid and water and thereafterdropping a mixture of the resulting sol and a gelling agent into an oilbath to form spherical particles of an alumina gel which are easilyconverted to a gamma-alumina carrier material by known methods; (2)forming an extrudate from the powder by established methods andthereafter rolling the extrudate particles on a spinning disc untilspherical particles are formed which can then be dried and calcined toform the desired particles of spherical carrier material; and (3)wetting the powder with a suitable peptizing agent and thereafterrolling particles of the powder into spherical masses of the desiredsize in much the same way that children have been known to make parts ofsnowmen by rolling snowballs down hills covered with wet snow. Thisalumina powder can also be formed in any other desired shape or type ofcarrier material known to those skilled in the art such as rods, pills,pellets, tablets, granules, extrudates and the like forms by methodswell known to the practitioners of the catalyst carrier material formingart. The preferred type of carrier material for the present invention isa cylindrical extrudate having a diameter of about 1/32" to about 1/8"(especially about 1/16") and a length to diameter (L/D) ratio of about1:1 to about 5:1, with a L/D ratio of about 2:1 being especiallypreferred. The especially preferred extrudate form of the carriermaterial is preferably prepared by mixing the alumina powder with waterand a suitable peptizing agent such as nitric acid, acetic acid,aluminum nitrate and the like material until an extrudable dough isformed. The amount of water added to form the dough is typicallysufficient to give a loss on ignition (LOI) at 500° C. of about 45 to 65wt. %, with a value of about 55 wt. % being especially preferred. On theother hand, the acid addition rate is generally sufficient to provideabout 2 to 7 wt. % of the volatile free alumina powder used in the mix,with a value of about 3 to 4% being especially preferred. The resultingdough is then extruded through a suitably sized die to form extrudateparticles. These particles are then dried at a temperature of about 500°to 800° F. for a period of about 0.1 to about 5 hours and thereaftercalcined at a temperature of about 900° F. to about 1500° F. for aperiod of about 0.5 to about 5 hours to form the preferred extrudateparticles of the Ziegler alumina carrier material. In addition, in someembodiments of the present invention the Ziegler alumina carriermaterial may contain minor proportions of other well known refractoryinorganic oxides such as silica, titanium dioxide, zirconium dioxide,chromium oxide, beryllium oxide, vanadium oxide, cesium oxide, hafniumoxide, zinc oxide, iron oxide, cobalt oxide, magnesia, boria, thoria,and the like materials which can be blended into the extrudable doughprior to the extrusion of same. In the same manner crystalline zeoliticaluminosilicates such as naturally occurring or synthetically preparedmordenite and/or faujasite, either in the hydrogen form or in a formwhich has been treated with a multivalent cation, such as a rare earth,can be incorporated into this carrier material by blending finelydivided particles of same into the extrudable dough prior to extrusionof same. A preferred carrier material of this type is substantially pureZiegler alumina having an apparent bulk density (ABD) of about 0.6 to 1g/cc (especially an ABD of about 0.7 to about 0.85 g/cc), a surface areaof about 150 to about 280 m² /g (preferably about 185 to about 235 m²/g), and a pore volume of about 0.3 to about 0.8 cc/g.

The expression "catalytically available nickel" as used herein isintended to mean the portion of the nickel component that is availablefor use in accelerating the particular hydrocarbon conversion reactionof interest. For certain types of carrier materials which can be used inthe preparation of the instant catalyst composite, it has been observedthat a portion of the nickel incorporated therein is essentiallybound-up in the crystal structure thereof in a manner which essentiallymakes it more a part of the refractory carrier material than acatalytically active component. Specific examples of this effect areobserved when the carrier material can form a refractory spinel orspinel-like structure with a portion of the nickel component and/or whena refractory nickel oxide or aluminate is formed by reaction of thecarrier material (or precursor thereof) with a portion of the nickelcomponent. When this effect occurs, it is only with great difficultythat the portion of the nickel bound-up with the support can be reducedto a catalytically active state and the conditions required to do thisare beyond the severity levels normally associated with hydrocarbonconversion conditions and are in fact likely to seriously damage thenecessary porous characteristics of the support. In the cases wherenickel can interact with the crystal structure of the support to rendera portion thereof catalytically unavailable, the concept of the presentinvention merely requires that the amount of nickel added to the subjectcatalyst be adjusted to satisfy the requirements of the support as wellas the catalytically available nickel requirements of the presentinvention. Against this background then, the hereinafter statedspecifications for oxidation state and dispension of the nickelcomponent are to be interpreted as directed to a description of thecatalytically available nickel. On the other hand, the specificationsfor the amount of nickel used are to be interpreted to include all ofthe nickel contained in the catalyst in any form.

One essential ingredient of the present catalytic composite is alanthanide series component. By the use of the generic expression"lanthanide series component" it is intended to cover the 15 innertransition metallic elements and mixtures thereof that are commonlyknown as the "lanthanide series metals" or "rare earth metals."Specifically, included within this definition are the followingelements: lanthanum, cerium, praseodymium, neodymium, promethium,samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium,thulium, ytterbium and lutetium. This component may be present in theinstant multimetallic composite in any form wherein substantially all ofthe lanthanide series metal is present in an oxidation state above thatof the corresponding metal such as in chemical combination with one ormore of the other ingredients of the composite, or as a chemicalcompound such as a lanthanide oxide, halide, oxyhalide, aluminate, andthe like. However, best results are believed to be obtained whensubstantially all of the lanthanide series component exists in the formof the corresponding oxide and the subsequently described oxidation andprereduction procedure is believed, on the basis of the availableevidence, to result in this condition. This lanthanide series componentmay be utilized in the composite in any amount which is catalyticallyeffective, with the preferred amount being about 0.01 to about 5 wt. %thereof, calculated on an elemental basis. Typically best results areobtained with about 0.05 to about 2 wt. % lanthanide series metal.According to one embodiment of the present invention, it is anespecially preferred practice to select the specific amount oflanthanide series element from within this broad weight range as afunction of the amount of the platinum group component, on an atomicbasis, as is explained hereinafter. The lanthanide series elements thatare especially preferred for purposes of the present invention arelanthanum, cerium, and neodymium, with neodymium giving best results.

The lanthanide series component may be incorporated into the catalyticcomposite in any suitable manner known to those skilled in the catalystformulation art which ultimately results in a uniform dispersion of thelanthanide series moiety in the carrier material. In addition, it may beadded at any stage of the preparation of the composite--either duringpreparation of the carrier material or thereafter--and the precisemethod of incorporation used is not deemed to be critical. However, bestresults are obtained when the lanthanide series component isincorporated in a manner such that is relatively uniformly distributedthroughout the carrier material in a positive oxidation state or a statewhich is easily converted to a positive oxidation state in thesubsequently described oxidation step. One preferred procedure forincorporating this component into the composite involves cogelling orcoprecipitating the lanthanide series component during the preparationof the preferred carrier material, alumina. This procedure usuallycomprehends the addition of a soluble, decomposable compound of alanthanide series element such as neodymium nitrate to the aluminahydrosol before it is gelled. The resulting mixture is then finished byconventional gelling, aging, drying and calcination steps as explainedhereinbefore. Another preferred way of incorporating this component isan impregnation step wherein the porous carrier material is impregnatedwith a suitable lanthanide series compound-containing solution eitherbefore, during or after the carrier material is calcined. Preferredimpregnation solutions are aqueous solutions of water-soluble,decomposable lanthanide series compounds such as a lanthanide acetate, alanthanide bromide, a lanthanide perchlorate, a lanthanide chloride, alanthanide iodide, a lanthanide nitrate, and the like compounds. Bestresults are ordinarily obtained when the impregnation solution is anaqueous solution of a lanthanide chloride or a lanthanide nitrate. Thislanthanide series component can be added to the carrier material, eitherprior to, simultaneously with, or after the other metallic componentsare combined therewith. Best results are usually achieved when thiscomponent is added simultaneously with the other metallic components. Infact, the preferred preparation procedure for the instant catalystinvolves a one step impregnation procedure with an acidic aqueousimpregnation solution containing chloroplatinic acid, a lanthanidenitrate, nickel chloride and hydrochloric acid.

A second essential ingredient of the subject catalyst is the platinumgroup component. That is, it is intended to cover the use of platinum,iridium, osmium, ruthenium, rhodium, palladium, or mixtures thereof, asa second component of the present composite. It is an essential featureof the present invention that substantially all of this platinum groupcomponent exists within the final catalytic composite in the elementalmetallic state. Generally, the amount of this component present in thefinal catalytic composite is small compared to the quantities of theother components combined therewith. In fact, the platinum groupcomponent generally will comprise about 0.01 to about 2 wt. % of thefinal catalytic composite, calculated on an elemental basis. Excellentresults are obtained when the catalyst contains about 0.05 to about 1wt. % of platinum, iridium, rhodium, or palladium metal. Particularlypreferred mixtures of these metals are platinum and iridium, andplatinum and rhodium.

This platinum group component may be incorporated in the catalyticcomposite in any suitable manner known to result in a relatively uniformdistribution of this component in the carrier material such ascoprecipitation or cogelation, ion exchange or impregnation. Thepreferred method of preparing the catalyst involves the utilization of asoluble, decomposable compound of platinum group metal to impregnate thecarrier material in a relatively uniform manner. For example, thiscomponent may be added to the support by commingling the latter with anaqueous solution of chloroplatinic or chloroiridic or chloropalladicacid. Other water-soluble compounds or complexes of platinum groupmetals may be employed in impregnation solutions and include ammoniumchloroplatinate, bromoplatinic acid, platinum trichloride, platinumtetrachloride hydrate, platinum dichlorocarbonyl dichloride,dinitrodiaminoplatinum, sodium tetranitroplatinate (II), palladiumchloride, palladium nitrate, palladium sulfate, diamminepalladium (II)hydroxide, tetramminepalladium (II) chloride, hexamminerhodium chloride,rhodium carbonylchloride, rhodium trichloride hydrate, rhodium nitrate,sodium hexachlororhodate (III), sodium hexanitrorhodate (III), iridiumtribromide, iridium dichloride, iridium tetrachloride, sodiumhexanitroiridate (III), iridium tribromide, iridium dichloride, iridiumtetrachloride, sodium hexanitroiridate (III), potassium or sodiumchloroiridate, potassium rhodium oxalate, etc. The utilization of aplatinum, iridium, rhodium, or palladium chloride compound, such aschloroplatinic, chloroiridic, or chloropalladic acid or rhodiumtrichloride hydrate, is preferred since it facilitates the incorporationof both the platinum group components and at least a minor quantity ofthe halogen component in a single step. Hydrogen chloride or the likeacid is also generally added to the impregnation solution in order tofurther facilitate the incorporation of the halogen component and theuniform distribution of the metallic components throughout the carriermaterial. In addition, it is generally preferred to impregnate thecarrier material after it has been calcined in order to minimize therisk of washing away the valuable platinum or palladium compounds;however, in some cases it may be advantageous to impregnate the carriermaterial when it is in a gelled state.

A third essential ingredient of the acidic multimetallic catalyticcomposite of the present invention is a nickel component. Although thiscomponent may be initially incorporated into the composite in manydifferent decomposable forms which are hereinafter stated, my basicfinding is that the catalytically active state for hydrocarbonconversion with this component is the elemental metallic state.Consequently, it is a feature of my invention that substantially all ofthe catalytically available nickel component exists in the catalyticcomposite either in the elemental metallic state or in a state which isreducible to the elemental state under hydrocarbon conversion conditionsor in a mixture of these states. Examples of this reducible state areobtained when the catalytically available nickel component is initiallypresent in the form of nickel oxide, halide, hydroxide, oxyhalide, andthe like reducible compounds. As a corollary to this basic finding onthe active state of the catalytically available nickel component, itfollows that the presence of catalytically available nickel in formswhich are not reducible at hydrocarbon conversion conditions is to bescrupulously avoided if the full benefits of the present invention areto be realized. Illustrative of these undesired forms are nickel sulfideand the nickel oxysulfur compounds such as nickel sulfate. Best resultsare obtained when the composite initially contains all of thecatalytically available nickel component in the elemental metallic stateor in a reducible oxide state or in a mixture of these states. Allavailable evidence indicates that the preferred preparation procedurespecifically described in Example I results in a catalyst having thecatalytically available nickel component in the elemental metallic stateor in a reducible oxide form. The nickel component may be utilized inthe composite in any amount which is catalytically effective, with thepreferred amount being about 0.05 to about 5 wt. % thereof, calculatedon an elemental nickel basis. Typically, best results are obtained withabout 0.1 to about 2.5 wt. % nickel. It is, additionally, preferred toselect the specific amount of nickel from within this broad weight rangeas a function of the amount of the platinum group component, on anatomic basis, as is explained hereinafter.

The nickel component may be incorporated into the catalytic composite inany suitable manner known to those skilled in the catalyst formulationart to result in a relatively uniform distribution of the catalyticallyavailable nickel in the carrier material such as coprecipitation,cogelation, ion exchange, impregnation, etc. In addition, it may beadded at any stage of the preparation of the composite--either duringpreparation of the carrier material or thereafter--since the precisemethod of incorporation used is not deemed to be critical. However, bestresults are obtained when the catalytically available nickel componentis relatively uniformly distributed throughout the carrier material in arelatively small particle or crystallite size, and the preferredprocedures are the ones that are known to result in a composite having arelatively uniform distribution of the catalytically available nickelmoiety in a relatively small particle size. One acceptable procedure forincorporating this component into the composite involves cogelling orcoprecipitating the nickel component during the preparation of thepreferred carrier material, alumina. This procedure usually comprehendsthe addition of a soluble, decomposable, and reducible compound ofnickel such as nickel chloride or nitrate to the alumina hydrosol beforeit is gelled. The resulting mixture is then finished by conventionalgelling, aging, drying, and calcination steps as explained hereinbefore.One preferred way of incorporating this component is an impregnationstep wherein the porous carrier material is impregnated with a suitablenickel-containing solution either before, during, or after the carriermaterial is calcined or oxidized. The solvent used to form theimpregnation solution may be water, alcohol, ether, or any othersuitable organic or inorganic solvent provided the solvent does notadversely interact with any of the other ingredients of the composite orinterfere with the distribution and reduction of the nickel component.Preferred impregnation solutions are aqueous solutions of water-soluble,decomposable, and reducible nickel compounds or complexes such as nickelbromate, nickel bromide, nickel perchlorate, nickel chloride, nickelfluoride, nickel iodide, nickel nitrate, hexamminenickel (II) chloride,diaquotetramminenickel (II) nitrate, hexamminenickel (II) nitrate, andthe like compounds or complexes. Best results are ordinarily obtainedwhen the impregnation solution is an aqueous acidic solution of nickelchloride or nickel nitrate. This nickel component can be added to thecarrier material, either prior to, simultaneously with, or after theother metallic components are combined therewith. Best results areusually achieved when this component is added simultaneously with theplatinum group and lanthanide series component via an acidic gaseousimpregnation solution.

It is essential to incorporate a halogen component into the acidicmultimetallic catalytic composite of the present invention. Although theprecise form of the chemistry of the association of the halogencomponent with the carrier material is not entirely known, it iscustomary in the art to refer to the halogen component as being combinedwith the carrier material, or with the other ingredients of the catalystin the form of the halide (e.g. as the chloride). This combined halogenmay be either fluorine, chlorine, iodine, bromine, or mixtures thereof.Of these, fluorine and, particularly, chlorine are preferred for thepurposes of the present invention. The halogen may be added to thecarrier material in any suitable manner, either during preparation ofthe support or before or after the addition of the other components. Forexample, the halogen may be added, at any stage of the preparation ofthe carrier material or to the calcined carrier material, as an aqueoussolution of a suitable decomposable halogen-containing compound such ashydrogen fluoride, hydrogen chloride, hydrogen bromide, ammoniumchloride, etc. The halogen component or a portion thereof, may becombined with the carrier material during the impregnation of the latterwith the platinum group, nickel, or lanthanide series components; forexample, through the utilization of a mixture of chloroplatinic acid andhydrogen chloride. In another situation, the alumina hydrosol which istypically utilized to form the preferred alumina carrier material maycontain halogen and thus contribute at least a portion of the halogencomponent to the final composite. For reforming, the halogen will betypically combined with the carrier material in an amount sufficient toresult in a final composite that contains about 0.1 to about 3.5%, andpreferably about 0.5 to about 1.5%, by weight of halogen, calculated onan elemental basis. In isomerization or hydrocracking embodiments, it isgenerally preferred to utilize relatively larger amounts of halogen inthe catalyst--typically, ranging up to about 10 wt. % halogen calculatedon an elemental basis, and more preferably, about 1 to about 5 wt. %. Itis to be understood that the specified level of halogen component in theinstant catalyst can be achieved or maintained during use in theconversion of hydrocarbons by continuously or periodically adding to thereaction zone a decomposable halogen-containing compound such as anorganic chloride (e.g. ethylene dichloride, carbon tetrachloride,t-butyl chloride) in an amount of about 1 to 100 wt. ppm. of thehydrocarbon feed, and preferably, about 1 to 10 wt. ppm.

One especially preferred optional constituent of the instant acidicmultimetallic catalytic composite is a Group IVA metallic component. Bythe use of the generic term "Group IVA metallic component" it isintended to cover the metals of Group IVA of the Periodic Table. Morespecifically, it is intended to cover: germanium, tin, lead, andmixtures of these metals. It is essential that substantially all of theGroup IVA metallic component is present in the final catalyst in anoxidation state above that of the elemental metal. In other words, thiscomponent may be present in chemical combination with one or more of theother ingredients of the composite, or as a chemical compound of theGroup IVA metal such as the oxide, sulfide, halide, oxyhalide,oxychloride, aluminate, and the like compounds. Based on the evidencecurrently available, it is believed that best results are obtained whensubstantially all of the Group IVA metallic component exists in thefinal composite in the form of the corresponding oxide such as the tinoxide, germanium oxide, and lead oxide, and the subsequently describedoxidation and reduction steps, that are preferably used in thepreparation of the instant composite, are believed to result in acatalytic composite which contains an oxide of the Group IVA metalliccomponent. Regardless of the state in which this component exists in thecomposite, it can be utilized therein in any amount which iscatalytically effective, with the preferred amount being about 0.01 toabout 5 wt. % thereof, calculated on an elemental basis and the mostpreferred amount being about 0.05 to about 2 wt. %.

This optional Group IVA component may be incorporated in the compositein any suitable manner known to the art to result in a uniformdispersion of the Group IVA moiety throughout the carrier material suchas, coprecipitation or cogelation with the porous carrier material, ionexchange with the carrier material, or impregnation of the carriermaterial at any stage in its preparation. It is to be noted that it isintended to include within the scope of the present invention allconventional procedures for incorporating a metallic component in acatalytic composite, and the particular method of incorporation used isnot deemed to be an essential feature of the present invention so longas the Group IVA component is uniformly distributed throughout theporous carrier material. One acceptable method of incorporating theGroup IVA component into the catalytic composite involved cogelling theGroup IVA component during the preparation of the preferred carriermaterial, alumina. This method typically involves the addition of asuitable soluble compound of the Group IVA metal of interest to thealumina hydrosol. The resulting mixture is then commingled with asuitable gelling agent, such as a relatively weak alkaline reagent, andthe resulting mixture is thereafter preferably gelled by dropping into ahot oil bath as explained hereinbefore. After aging, drying, andcalcining the resulting particles, there is obtained an intimatecombination of the oxide of the Group IVA metal and alumina. Onepreferred method of incorporating this component into the compositeinvolves utilization of a soluble decomposable compound of theparticular Group IVA metal of interest to impregnate the porous carriermaterial either before, during, or after the carrier material iscalcined. In general, the solvent used during this impregnation step isselected on the basis of its capability to dissolve the desired GroupIVA compound without affecting the porous carrier material which is tobe impregnated; ordinarily, good results are obtained when water is thesolvent; thus the preferred Group IVA compounds for use in thisimpregnation step are typically water-soluble and decomposable. Examplesof suitable Group IVA compounds are: germanium difluoride, germaniumtetra-alkoxide, germanium dioxide, germanium tetrafluoride, germaniummonosulfide, tin chloride, tin bromide, tin dibromide di-iodide, tindichloride di-iodide, tin chromate, tin difluoride, tin tetraiodide, tinsulfate, tin tartrate, lead acetate, lead bromate, lead bromide, leadchlorate, lead chloride, lead citrate, lead formate, lead lactate, leadmalate, lead nitrate, lead nitrite, lead dithionate, and the likecompounds. In the case where the Group IVA component is germanium, apreferred impregnation solution is germanium tetrachloride dissolved inanhydrous alcohol. In the case of tin, tin chloride dissolved in wateris preferred. In the case of lead, lead nitrate dissolved in water ispreferred. Regardless of which impregnation solution is utilized, theGroup IVA component can be impregnated either prior to, simultaneouslywith, or after the other metallic components are added to the carriermaterial. Ordinarily, best results are obtained when this component isadded prior to or simultaneously with the other metallic components ofthe composite. Likewise, best results are ordinarily obtained when theGroup IVA component is germanium oxide or tin oxide.

Regarding especially preferred amounts of the various metalliccomponents of the subject catalyst, I have found it to be a goodpractice to specify the amounts of the nickel, lanthanide series, and(when used) the Group IVA metallic components as a function of theamount of the platinum group component. On this basis, the amount of thenickel component is ordinarily selected so that the atomic ratio ofnickel to platinum group metal contained in the composite is about 0.1:1to about 66:1, with the preferred range being about 0.4:1 to about 18:1.Similarly, the amount of the lanthanide series component is ordinarilyselected to produce a composite containing an atomic ratio of lanthanideseries metal to platinum group metal of about 0.1:1 to about 20:1, withthe preferred range being about 1:1 to about 10:1. The amount of theoptional Group IVA metallic component is likewise selected so that theatomic ratio of Group IVA metal to platinum group metal is 0.05:1 toabout 10:1, with best results obtained when this ratio is fixed on thebasis of the individual Group IVA species as follows: (1) for germanium,it is about 0.3:1 to 10:1 and most preferably about 0.6:1 to 6:1; (2)for tin, it is about 0.1:1 to 3:1 and most preferably about 0.5:1 to1.5:1, and (3) for lead, it is about 0.05:1 to 0.9:1 and most preferablyabout 0.1:1 to 0.75:1.

Another significant parameter for the instant catalyst is the "totalmetals content" which is defined to be the sum of the platinum groupcomponent, the nickel component, and the lanthanide series component,calculated on an elemental basis. Good results are ordinarily obtainedwith the subject catalyst when this parameter is fixed at a value ofabout 0.15 to about 4 wt. %, with best results ordinarily achieved at ametals loading of about 0.3 to about 3 wt. %.

In embodiments of the present invention wherein the instantmulti-metallic catalytic composite is used for the dehydrogenation ofdehydrogenatable hydrocarbons or for the hydrogenation of hydrogenatablehydrocarbons, it is ordinarily a preferred practice to include an alkalior alkaline earth metal component in the composite and to minimize oreliminate the halogen component. More precisely, this optionalingredient is selected from the group consisting of the compounds of thealkali metals--cesium, rubidium, potassium, sodium, and lithium--and thecompounds of the alkaline earth metals--calcium, strontium, barium, andmagnesium. Generally, good results are obtained in these embodimentswhen this component constitutes about 0.1 to about 5 wt. % of thecomposite, calculated on an elemental basis. This optional alkali oralkaline earth metal component can be incorporated in the composite inany of the known ways, with impregnation with an aqueous solution of asuitable water-soluble, decomposable compound being preferred.

Another optional ingredient for the multimetallic catalyst of thepresent invention is a Freidel-Crafts metal halide component. Thisingredient is particularly useful in hydrocarbon conversion embodimentsof the present invention wherein it is preferred that the catalystutilized has a strong acid or cracking function associatedtherewith--for example, an embodiment wherein hydrocarbons are to behydrocracked or isomerized with the catalyst of the present invention.Suitable metal halides of the Friedel-Crafts type include aluminumchloride, aluminum bromide, ferric chloride, ferric bromide, zincchloride, and the like compounds, with the aluminum halides andparticularly aluminum chloride ordinarily yielding best results.Generally, this optional ingredient can be incorporated into thecomposite of the present invention by any of the conventional methodsfor adding metallic halides of this type; however, best results areordinarily obtained when the metallic halide is sublimed onto thesurface of the carrier material according to the preferred methoddisclosed in U.S. Pat. No. 2,999,074. The component can generally beutilized in any amount which is catalytically effective, with a valueselected from the range of about 1 to about 100 wt. % of the carriermaterial generally being preferred.

Regardless of the details of how the components of the catalyst arecombined with the porous carrier material, the final catalyst generallywill be dried at a temperature of about 200° to about 600° F. for aperiod of at least about 2 to about 24 hours or more, and finallycalcined or oxidized at a temperature of about 700° F. to about 1100° F.in an air to oxygen atmosphere for a period of about 0.5 to about 10hours in order to convert substantially all of the metallic componentsto the corresponding oxide form. Because a halogen component is utilizedin the catalyst, best results are generally obtained when the halogencontent of the catalyst is adjusted during the oxidation step byincluding a halogen or a halogen-containing compound such as HCl or anHCl-producing substance in the air or oxygen atmosphere utilized. Inparticular, when the halogen component of the catalyst is chlorine, itis preferred to use a mole ratio of H₂ O to HCl of about 5:1 to about100:1 during at least a portion of the oxidation step in order to adjustthe final chlorine content of the catalyst to a range of about 0.1 toabout 3.5 wt. %. Preferably, the duration of this halogenation step isabout 1 to 5 hours.

The resultant oxidized catalytic composite is preferably subjected to asubstantially water-free reduction step prior to its use in theconversion of hydrocarbons. This step is designed to selectively reducethe platinum group component to the elemental metallic state and toinsure a uniform and finely divided dispersion of the metalliccomponents throughout the carrier material, while maintaining thelanthanide series component in a positive oxidation state. Preferably, asubstantially pure and dry hydrogen stream (i.e. less than 20 vol. ppmH₂ O) is used as the reducing agent in this step. The reducing agent iscontacted with the oxidized catalyst at conditions including a reductiontemperature of about 800° F. to about 1200° F., preferably about 800° F.to about 1000° F., a gas hourly space velocity sufficient to rapidlydissipate any local concentration of water formed during the reductionprocedure, and a period of time of about 0.5 to 10 hours effective toreduce substantially all of the platinum group component to theelemental metallic state while maintaining the lanthanide seriescomponent in an oxidation state above that of the elemental metal. Ifthis reduction step is performed with a hydrocarbon-free hydrogen streamat the temperature indicated, and if the catalytically available nickelcomponent is properly distributed in the carrier material in the oxideform, a substantial portion of the catalytically available nickelcomponent may not be reduced in this step. However, once the catalystsees a flowing mixture of hydrogen and hydrocarbon (such as during thestarting-up and lining-out of the hydrocarbon conversion process usingsame), at least a major portion and typically substantially all of thecatalytically available nickel component is quickly reduced at thespecified reduction temperature range. This reduction treatment may beperformed in situ as part of the start-up sequence if precautions aretaken to predry the plant to a substantially water-free state and ifsubstantially water-free hydrogen stream is used.

The resulting reduced catalytic composite is, in accordance with thebasic concept of the present invention, preferably maintained in asulfur-free state both during its preparation and thereafter during itsuse in the conversion of hydrocarbons. As indicated previously, thebeneficial interaction of the catalytically available nickel componentwith the other ingredients of the present catalytic composite iscontingent upon the maintenance of the nickel moiety in a highlydispersed, readily reducible state in the carrier material. Sulfur inthe form of sulfide adversely interferes with both the dispersion andreducibility of the catalytically available nickel component andconsequently it is a highly preferred practice to avoid presulfiding theselectively reduced acidic multimetallic catalyst resulting from thereduction step. Once the catalyst has been exposed to hydrocarbon for asufficient period of time to lay down a protective layer of carbon orcoke on the surface thereof, the sulfur sensitivity of the resultingcarbon-containing composite changes rather markedly and the presence ofsmall amounts of sulfur can be tolerated without permanently disablingthe catalyst. The exposure of the freshly reduced catalyst to sulfur canseriously damage the nickel component thereof and consequentlyjeopardize the superior performance characteristics associatedtherewith. However, once a protective layer of carbon is established onthe catalyst, the sulfur deactivation effect is less permanent andsulfur can be purged therefrom by exposure to a sulfur-free hydrogenstream at a temperature of about 800° to 1100° F.

According to the present invention, a hydrocarbon charge stock andhydrogen are contacted with the instant acidic multimetallic catalyst ina hydrocarbon conversion zone. This contacting may be accomplished byusing the catalyst in a fixed bed system, a moving bed system, afluidized bed system, or in a batch type operation, however, in view ofthe danger of attrition losses of the valuable catalyst and ofwell-known operational advantages, it is preferred to use either a fixedbed system or a dense-phase moving bed system such as is shown in U.S.Pat. No. 3,725,249. It is also contemplated that the contacting step canbe performed in the presence of a physical mixture of particles of thecatalyst of the present invention and particles of a conventionaldual-function catalyst of the prior art. In a fixed bed system, ahydrogen-rich gas and the charge stock are preheated by any suitableheating means to the desired reaction temperature and then are passedinto a conversion zone containing a fixed bed of the acidicmultimetallic catalyst. It is, of course, understood that the conversionzone may be one or more separate reactors with suitable meanstherebetween to insure that the desired conversion temperature ismaintained at the entrance to each reactor. It is also important to notethat the reactants may be contacted with the catalyst bed in eitherupward, downward, or radial flow fashion with the latter beingpreferred. In addition, the reactants may be in the liquid phase, amixed liquid-vapor phase, or a vapor phase when they contact thecatalyst, with best results obtained in the vapor phase.

In the case where the acidic multimetallic catalyst of the presentinvention is used in a reforming operation, the reforming system willtypically comprise a reforming zone containing one or more fixed beds ordense-phase moving beds of the catalysts. In a multiple bed system, itis, of course, within the scope of the present invention to use thepresent catalyst in less than all of the beds with a conventionaldual-function catalyst being used in the remainder of the beds. Thisreforming zone may be one or more separate reactors with suitableheating means therebetween to compensate for the endothermic nature ofthe reactions that take place in each catalyst bed. The hydrocarbon feedstream that is charged to this reforming system will comprisehydrocarbon fractions containing naphthenes and paraffins that boilwithin the gasoline range. The preferred charge stocks are thoseconsisting essentially of naphthenes and paraffins, although in somecases aromatics and/or olefins may also be present. This preferred classincludes straight run gasolines, natural gasolines, synthetic gasolines,partially reformed gasolines, and the like. On the other hand, it isfrequently advantageous to charge thermally or catalytically crackedgasolines or higher boiling fractions thereof. Mixtures of straight runand cracked gasolines can also be used to advantage. The gasoline chargestock may be a full boiling gasoline having an initial boiling point offrom about 50° to about 150° F. and an end boiling point within therange of from about 325° to about 425° F., or may be a selected fractionthereof which generally will be a higher boiling fraction commonlyreferred to as a heavy naphtha--for example, a naphtha boiling in therange of C₇ to 400° F. In some cases, it is also advantageous to chargepure hydrocarbons or mixtures of hydrocarbons that have been extractedfrom hydrocarbon distillates--for example, straight-chainparaffins--which are to be converted to aromatics. It is preferred thatthese charge stocks be treated by conventional catalytic pretreatmentmethods such as hydrorefining, hydrotreating, hydrodesulfurization,etc., to remove substantially all sulfurous, nitrogenous, andwater-yielding contaminants and to saturate any olefins that may becontained therein.

In other hydrocarbon conversion embodiments, the charge stock will be ofthe conventional type customarily used for the particular kind ofhydrocarbon conversion being effected. For example, in a typicalisomerization embodiment the charge stock can be a paraffinic stock richin C₄ to C₈ normal paraffins, or a normal butane-rich stock, or ann-hexane-rich stock, or a mixture of xylene isomers, or anolefin-containing stock, etc. In a dehydrogenation embodiment, thecharge stock can be any of the known dehydrogenatable hydrocarbons suchas an aliphatic compound containing 2 to 30 carbon atoms per molecule, aC₄ to C₃₀ normal paraffin, a C₈ to C₁₂ alkylaromatic, a naphthene, andthe like. In hydrocracking embodiments, the charge stock will betypically a gas oil, heavy cracked cycle oil, etc. In addition,alkylaromatics, olefins, and naphthenes can be conveniently isomerizedby using the catalyst of the present invention. Likewise, purehydrocarbons or substantially pure hydrocarbons can be converted to morevaluable products by using the acidic multimetallic catalyst of thepresent invention in any of the hydrocarbon conversion processes, knownto the art, that use a duel-function catalyst.

Since sulfur has a high affinity for nickel at hydrocarbon conversionconditions, best results are achieved in the conversion of hydrocarbonswith the instant acidic multimetallic catalytic composite when thecatalyst is used in a substantially sulfur-free environment. This isparticularly true in the catalytic reforming embodiment of the presentinvention. The expression "substantially sulfur-free environment" isintended to mean that the total amount (expressed as equivalentelemental sulfur) of sulfur or sulfur-containing compounds, which arecapable of producing a metallic sulfide at the reaction conditions used,entering the reaction zone containing the instant catalyst from anysource is continuously maintained at an amount equivalent to less than10 wt. ppm. of the hydrocarbon charge stock, more preferably less than 5wt. ppm., and most preferably less than 1 wt. ppm. Since in the ordinaryoperation of a conventional catalytic reforming process, whereininfluent hydrogen is autogenously produced, the prime source for anysulfur entering the reforming zone is the hydrocarbon charge stock,maintaining the charge stock substantially free of sulfur is ordinarilysufficient to ensure that the environment containing the catalyst ismaintained in the substantially sulfur-free state. More specifically,since hydrogen is a by-product of the catalytic reforming process,ordinarily the input hydrogen stream required for the process isobtained by recycling a portion of the hydrogen-rich stream recoveredfrom the effluent withdrawn from the reforming zone. In this typicalsituation, this recycle hydrogen stream will ordinarily be substantiallyfree of sulfur if the charge stock is maintained free of sulfur. Ifautogenous hydrogen is not utilized, then, of course, the concept of thepresent invention requires that the input hydrogen stream be maintainedsubstantially sulfur-free; that is, less than 10 vol. ppm. of H₂ S,preferably less than 5 vol. ppm., and most preferably less than 1 vol.ppm.

The only other possible sources of sulfur that could interfere with theperformance of the instant catalyst are sulfur that is initiallycombined with the catalyst and/or with the plant hardware. As indicatedhereinbefore, a highly preferred feature of the present acidicmultimetallic catalyst is that it is maintained in a substantiallysulfur-free state; therefore, sulfur released from the catalyst is notusually a problem in the present process. Hardware sulfur is ordinarilynot present in a new plant; it only becomes a problem when the presentprocess is to be implemented in a plant that has been service with asulfur-containing feedstream. In this latter case, the preferredpractice of the present invention involves an initial pretreatment ofthe sulfur-containing plant in order to remove substantially all of thedecomposable hardware sulfur therefrom. This can be easily accomplishedby any of the techniques for stripping sulfur from hardware known tothose in the art; for example, by the circulation of a substantiallysulfur-free hydrogen stream through the internals of the plant at arelatively high temperature of about 800° to about 1200° F. until the H₂S content of the effluent gas stream drops to a relatively lowlevel--typically, less than 5 vol. ppm. and preferably less than 2 vol.ppm. In sum, the preferred sulfur-free feature of the present inventionrequires that the total amount of detrimental sulfur entering thehydrocarbon conversion zone containing the hereinbefore described acidicmultimetallic catalyst must be continuously maintained at asubstantially low level; specifically, the total amount of sulfur mustbe held to a level equivalent to less than 10 wt. ppm., and preferablyless than 1 wt. ppm., of the feed.

In the case where the sulfur content of the feed stream for the presentprocess is greater than the amounts previously specified, it is, ofcourse, necessary to treat the charge stock in order to remove theundesired sulfur contaminants therefrom. This is easily accomplished byusing any one of the conventional catalytic pretreatment methods such ashydrorefining, hydrotreating, hydrodesulfurization, and the like toremove substantially all sulfurous, nitrogenous, and water-yieldingcontaminants from this feedstream. Ordinarily, this involves subjectingthe sulfur-containing feedstream to contact with a suitablesulfur-resistant hydrorefining catalyst in the presence of hydrogenunder conversion conditions selected to decompose sulfur contaminantscontained therein and form hydrogen sulfide. The hydrorefining catalysttypically comprises one or more of the oxides or sulfides of thetransition metals of Groups VI and VIII of the Periodic Table. Aparticularly preferred hydrorefining catalyst comprises a combination ofa metallic component from the iron group metals of Group VIII and of ametallic component of the Group VI transition metals combined with asuitable porous refractory support. Particularly good results have beenobtained when the iron group component is cobalt and/or nickel and theGroup VI transition metal is molybdenum or tungsten. The preferredsupport for this type of catalyst is a refractory inorganic oxide of thetype previously mentioned. For example, good results are obtained with ahydrorefining catalyst comprising cobalt oxide and molybdenum oxidesupported on a carrier material comprising alumina and silica. Theconditions utilized in this hydrorefining step are ordinarily selectedfrom the following ranges: a temperature of about 600° to about 950° F.,a pressure of about 500 to about 5000 psig., a liquid hourly spacevelocity of about 1 to about 20 hr.⁻¹, and a hydrogen circulation rateof about 500 to about 10,000 standard cubic feet of hydrogen per barrelof charge. After this hydrorefining step, the hydrogen sulfide, ammonia,and water liberated therein, are then easily removed from the resultingpurified charge stock by conventional means such as a suitable strippingoperation. Specific hydrorefining conditions are selected from theranges given above as a function of the amounts and kinds of the sulfurcontaminants in the feedstream in order to produce a substantiallysulfur-free charge stock which is then charged to the process of thepresent invention.

In a reforming embodiment, it is generally preferred to utilize thenovel acidic multimetallic catalytic composite in a substantiallywater-free environment. Essential to the achievement of this conditionin the reforming zone is the control of the water level present in thecharge stock and the hydrogen stream which are charged to the zone. Bestresults are ordinarily obtained when the total amount of water enteringthe conversion zone from any source is held to a level less than 20 ppm.and preferably less than 5 ppm. expressed as weight of equivalent waterin the charge stock. In general, this can be accomplished by carefulcontrol of the water present in the charge stock and in the hydrogenstream. The charge stock can be dried by using any suitable drying meansknown to the art, such as a conventional solid adsorbent having a highselectivity for water, for instance, dehydrated sodium or calciumzeolitic crystalline aluminosilicates, silica gel, activated alumina,molecular sieves, anhydrous calcium sulfate, high surface area sodium,and the like adsorbents. Similarly, the water content of the chargestock may be adjusted by suitable stripping operations in afractionation column or like device. And in some cases, a combination ofadsorbent drying and distillation drying may be used advantageously toeffect almost complete removal of water from the charge stock. In anespecially preferred mode of operation, the charge stock is dried to alevel corresponding to less than 5 wt. ppm. of H₂ O equivalent. Ingeneral, it is preferred to maintain the hydrogen stream entering thehydrocarbon conversion zone at a level of about 10 vol. ppm. of water orless and most preferably about 5 vol. ppm. or less. If the water levelin the hydrogen stream is too high, drying of same can be convenientlyaccomplished by contacting the hydrogen stream with a suitable desiccantsuch as those mentioned above.

In the reforming embodiment, an effluent stream is withdrawn from thereforming zone and passed through a cooling means to a separation zone,typically maintained at about 25° to 150° F., wherein a hydrogen-richgas stream is separated from a high octane liquid product stream,commonly called an unstabilized reformate. When the water level in thehydrogen stream is outside the range previously specified, at least aportion of this hydrogen-rich gas stream is withdrawn from theseparating zone and passed through an adsorption zone containing anadsorbent selective for water. The resultant substantially water-freehydrogen stream can then be recycled through suitable compressing meansback to the reforming zone. The liquid phase from the separating zone istypically withdrawn and commonly treated in a fractionating system inorder to adjust the butane concentration, thereby controlling front-endvolatility of the resulting reformate.

The operating conditions utilized in the numerous hydrocarbon conversionembodiments of the present invention are in general those customarilyused in the art for the particular reaction, or combination ofreactions, that is to be effected. For instance, alkylaromatic, olefin,and paraffin isomerization conditions include: a temperature of about32° F. to about 1000° F. and preferably from about 75° to about 600° F.;a pressure of atmospheric to about 100 atmospheres; a hydrogen tohydrocarbon mole ratio of about 0.5:1 to about 20:1, and an LHSV(calculated on the basis of equivalent liquid volume of the charge stockcontacted with the catalyst per hour divided by the volume of conversionzone containing catalyst) of about 0.2 hr.⁻¹ to 10 hr.⁻¹.Dehydrogenation conditions include: a temperature of about 700° to about1250° F., a pressure of about 0.1 to about 10 atmospheres, a liquidhourly space velocity of about 1 to 40 hr.⁻¹, and a hydrogen tohydrocarbon mole ratio of about 1:1 to 20:1. Likewise, typicallyhydrocracking conditions include: a pressure of about 500 psig. to about3000 psig., a temperature of about 400° F. to about 900° F., an LHSV ofabout 0.1 hr.⁻¹ to about 10 hr.⁻¹, and hydrogen circulation rates ofabout 1000 to 10,000 SCF per barrel of charge.

In the reforming embodiment of the present invention, the pressureutilized is selected from the range of about 0 psig, to about 1000psig., with the preferred pressure being about 50 psig. to about 600psig. Particularly good results are obtained at low or moderatepressure; namely, a pressure of about 100 to 450 psig. In fact, it is asingular advantage of the present invention that it allows stableoperation at lower pressure than have heretofore been successfullyutilized in so-called "continuous" reforming systems (i.e. reforming forperiods of about 15 to about 200 or more barrels of charge per pound ofcatalyst without regeneration) with all platinum monometallic catalyst.In other words, the acidic multimetallic catalyst of the presentinvention allows the operation of a continuous reforming system to beconducted at lower pressure (i.e. 100 to about 350 psig) for about thesame or better catalyst cycle life before regeneration as has beenheretofore realized with conventional monometallic catalysts at higherpressure (i.e. 400 to 600 psig). On the other hand, the extraordinaryactivity and activity-stability characteristics of the catalyst of thepresent invention enables reforming conditions conducted at pressures of400 to 600 psig. to achieve substantially increased catalyst cycle lifebefore regeneration.

The temperature required for reforming with the instant catalyst ismarkedly lower than that required for a similar reforming operationusing a high quality catalyst of the prior art. This significant anddesirable feature of the present invention is a consequence of theextraordinary activity of the acidic multimetallic catalyst of thepresent invention for the octane-upgrading reactions that are preferablyinduced in a typical reforming operation. Hence, the present inventionrequires a temperature in the range of from about 800° F. to about 1100°F. and preferably about 900° F. to about 1050° F. As is well known tothose skilled in the continuous reforming art, the initial selection ofthe temperature within this broad range is made primarily as a functionof the desired octane of the product reformate considering thecharacteristics of the charge stock and of the catalyst. Ordinarily, thetemperature then is thereafter slowly increased during the run tocompensate for the inevitable deactivation that occurs to provide aconstant octane product. Therefore, it is a feature of the presentinvention that not only is the initial temperature requirementsubstantially lower, but also the rate at which the temperature isincreased in order to maintain a constant octane product issubstantially lower for the catalyst of the present invention than foran equivalent operation with a high quality reforming catalyst which ismanufactured in exactly the same manner as the catalyst of the presentinvention except for the inclusion of the nickel and lanthanide seriescomponents. Moreover, for the catalyst of the present invention, theC₅ + yield loss for a given temperature increase is substantially lowerthan for a high quality reforming catalyst of the prior art. Theextraordinary activity of the instant catalyst can be utilized in anumber of highly beneficial ways to enable increased performance of acatalytic reforming process relative to that obtained in a similaroperation with a monometallic or bimetallic catalyst of the prior art,some of these are: (1) Octane number of C₅ + product can besubstantially increased without sacrificing catalyst run length. (2) Theduration of the process operation (i.e. catalyst run length or cyclelife) before regeneration becomes necessary can be significantlyincreased. (3) C₅ + yield can be increased by lowering average reactorpressure with no change in catalyst run length. (4) Investment costs canbe lowered without any sacrifice in cycle life by lowering recycle gasrequirements thereby saving on capital cost for compressor capacity orby lowering initial catalyst loading requirements thereby saving on costof catalyst and on capital cost of the reactors. (5) Throughput can beincreased sharply at no sacrifice in catalyst cycle life if sufficientheater capacity is available.

The reforming embodiment of the present invention also typicallyutilizes sufficient hydrogen to provide an amount of about 1 to about 20moles of hydrogen per mole of hydrocarbon entering the reforming zone,with excellent results being obtained when about 2 to about 6 moles ofhydrogen are used per mole of hydrocarbon. Likewise, the liquid hourlyspace velocity (LHSV) used in reforming is selected from the range ofabout 0.1 to about 10 hr.⁻¹, with a value in the range of about 1 toabout 5 hr.⁻¹ being preferred. In fact, it is a feature of the presentinvention that it allows operations to be conducted at higher LHSV thannormally can be stably achieved in a continuous reforming process with ahigh quality reforming catalyst of the prior art. This last feature isof immense economic significance because it allows a continuousreforming process to operate at the same throughput level with lesscatalyst inventory or at greatly increased throughput level with thesame catalyst inventory than that heretofore used with conventionalreforming catalyst at no sacrifice in catalyst life before regeneration.

The following working examples are given to illustrate further thepreparation of the acidic multimetallic catalytic composite of thepresent invention and the use thereof in the conversion of hydrocarbons.It is understood that the examples are intended to be illustrativerather than restrictive.

EXAMPLE I

An alumina carrier material comprising 1/16 inch spheres is prepared by:forming an aluminum hydroxyl chloride sol by dissolving substantiallypure aluminum pellets in a hydrochloric acid solution, addinghexamethylenetetramine to the resulting sol, gelling the resultingsolution by dropping it into an oil bath to form spherical particles ofan alumina hydrogel, aging and washing the resulting particles, andfinely drying and calcining the aged and washed particles to formspherical particles of gamma-alumina containing about 0.3 wt.% combinedchloride. Additional details as to this method of preparing thepreferred carrier material are given in the teachings of U.S. Pat. No.2,620,314.

An aqueous acidic sulfur-free impregnation solution containingchloroplatinic acid, nickel chloride, neodymium nitrate and hydrogenchloride is then prepared. The alumina carrier material is thereafteradmixed with the impregnation solution. The amount of reagents containedin this impregnation solution are calculated to result in a finalcomposite containing, on an elemental basis, 0.3 wt.% platinum, 1.0 wt.%neodymium, and 1.0 wt.% nickel. In order to insure uniform dispersion ofthe metallic components throughout the carrier material, the amount ofhydrochloric acid used is about 12 wt.% of the alumina particles. Thisimpregnation step is performed by adding the carrier material particlesto the impregnation mixture with constant agitation. In addition, thevolume of the solution is approximately the same as the bulk volume ofthe carrier material particles. The impregnation mixture is maintainedin contact with the carrier material particles for a period of about 1/2to about 3 hours at a temperature of about 70° F. Thereafter, thetemperature of the impregnation mixture is raised to about 225° F. andthe excess solution was evaporated in a period of about 1 hour. Theresulting dried impregnated particles are then subjected to an oxidationtreatment in a sulfur-free dry air stream at a temperature of about 930°F. and a GHSV of about 500 hr.⁻¹ for about 1/2 hour. This oxidation stepis designed to convert substantially all of the metallic ingredients tothe corresponding oxide forms. The resulting oxidized spheres aresubsequently contacted in a halogen-treating step with a sulfur-free airstream containing H₂ O and HCl in a mole ratio of about 30:1 for about 2hours at 930° F. and a GHSV of about 500 hr.⁻¹ in order to adjust thehalogen content of the catalyst particles to a value of about 1 wt.%.The halogen-treated spheres are thereafter subjected to a secondoxidation step with a dry sulfur-free air stream at 930° F. and a GHSVof 500 hr.⁻¹ for an additional period of about 1/2 hour.

The oxidized and halogen-treated catalyst particles are then subjectedto a dry prereduction treatment, designed to reduce substantially all ofthe platinum component to the elemental metallic state while maintainingthe neodymium component in a positive oxidation state, by contactingthem for about 1 hour with a substantially hydrocarbon-free andsulfur-free hydrogen stream containing less than 5 vol. ppm. H₂ O at atemperature of about 930° F., a pressure slightly above atmospheric, anda flow rate of the hydrogen stream through the catalyst particlescorresponding to a GHSV of about 400 hr.⁻¹.

A sample of the resulting reduced catalyst particles is analyzed andfound to contain, on an elemental basis, about 0.3 wt.% platinum, about1.0 wt.% nickel, about 1.0 wt.% neodymium, and about 1 wt.% chloride.This corresponds to an atomic ratio of neodymium to platinum of 4.5:1and to an atomic ratio of nickel to platinum of 11:1.

EXAMPLE II

A portion of the spherical acidic multimetallic catalyst particlesproduced by the method described in Example I is loaded into a scalemodel of a continuous, fixed bed reforming plant of conventional design.In this plant a heavy Kuwait naphtha and hydrogen are continuouslycontacted at reforming conditions: a liquid hourly space velocity of 3.0hr.⁻¹, a pressure of 300 psig., a hydrogen-containing recycle gas tohydrocarbon mole ratio of 5:1, and a temperature sufficient tocontinuously produce a C₅ + reformate of 100 F-1 clear. It is to benoted that these are exceptionally severe conditions.

The heavy Kuwait naphtha has an API gravity at 60° F. of 60.4, aninitial boiling point of 184° F., a 50% boiling point of 256° F., and anend boiling point of 360° F. In addition, it contains about 8 vol.%aromatics, 71 vol.% paraffins, 21 vol.% naphthenes, 0.5 weight parts permillion sulfur, and 5 to 8 weight parts per million water. The F-1 clearoctane number of the raw stock is 40.0.

The fixed bed reforming plant is made up of a reactor containing theacidic multimetallic catalyst, a hydrogen separation zone, a debutanizercolumn, and suitable heating, pumping, cooling, and controlling means.In this plant, a hydrogen recycle stream and the charge stock arecommingled and heated to the desired temperature. The resultant mixtureis then passed downflow into a reactor containing the catalyst as afixed bed. An effluent stream is then withdrawn from the bottom of thereactor, cooled to about 55° F. and passed to a separating zone whereina hydrogen-rich and methane-rich gaseous phase separates from a liquidhydrocarbon phase. A portion of the gaseous phase is continuously passedthrough a high surface sodium scrubber and the resulting waterfreehydrogen-containing stream recycled to the reactor in order to supplyhydrogen thereto, and the excess gaseous phase over that needed forplant pressure is recovered as excess separator gas. The liquidhydrocarbon phase from the hydrogen separating zone is withdrawntherefrom and passed to a debutanizer column of conventional designwherein light ends are taken overhead as debutanizer gas and a C₅ +reformate stream recovered as bottoms.

The test run is continued for a catalyst life of about 10 barrels ofcharge per pound of catalyst utilized, and it is determined that theactivity, selectivity, and stability characteristics of the presentmultimetallic catalyst are vastly superior to those observed in asimilar type test with a conventional all platinum commercial reformingcatalyst. More specifically, the results obtained from the subjectcatalyst are superior to the platinum metal-containing catalyst of theprior art in the area of initial and average temperature required tomake octane, methane production, average C₅ + yield at octane, averagerate of temperature increase necessary to maintain octane and C₅ + yielddecline rate.

It is intended to cover by the following claims, all changes andmodifications of the above disclosure of the present invention whichwould be self-evident to a man of ordinary skill in the catalystformulation art or the hydrocarbon conversion art.

I claim as my invention:
 1. A process for converting a hydrocarbon whichcomprises contacting the hydrocarbon at hydrocarbon conversionconditions with an acidic catalytic composite comprising a porouscarrier material containing, on an elemental basis, about 0.01 to about2 wt.% platinum group metal, about 0.05 to about 5 wt.% nickel, about0.01 to about 5 wt.% lanthanide series metal, and about 0.1 to about 3.5wt.% halogen; wherein the platinum group metal, catalytically availablenickel, and lanthanide series metal are uniformly dispersed throughoutthe porous carrier material; wherein substantially all of the lanthanideseries metal is present in a positive oxidation state; whereinsubstantially all of the platinum group metal is present in theelemental metallic state; and wherein substantially all of thecatalytically available nickel is present in the elemental metallicstate or in a state which is reducible to the elemental metallic stateunder hydrocarbon conversion conditions or in a mixture of these states.2. A process as defined in claim 1 wherein the platinum group metal isplatinum.
 3. A process as defined in claim 1 wherein the platinum groupmetal is iridium.
 4. A process as defined in claim 1 wherein theplatinum group metal is rhodium.
 5. A process as defined in claim 1wherein the platinum group metal is palladium.
 6. A process as definedin claim 1 wherein the porous carrier material is a refractory inorganicoxide.
 7. A process as defined in claim 6 wherein the refractoryinorganic oxide is alumina.
 8. A process as defined in claim 1 whereinthe halogen is combined chloride.
 9. A process as defined in claim 1wherein the lanthanide series component is neodymium.
 10. A process asdefined in claim 1 wherein the lanthanide series component is cerium.11. A process as defined in claim 1 wherein the lanthanide seriescomponent is lanthanum.
 12. A process as defined in claim 1 wherein theatomic ratio of lanthanide series metal to platinum group metalcontained in the composite is about 0.1:1 to about 20:1.
 13. A processas defined in claim 1 wherein the atomic ratio of nickel to platinumgroup metal contained in the composite is about 0.1:1 to about 66:1. 14.A process as defined in claim 1 wherein substantially all of thecatalytically available nickel contained in the composite is present inthe elemental metallic state after the process is started-up andlined-out at hydrocarbon conversion conditions.
 15. A process as definedin claim 1 wherein substantially all of the lanthanide series metal ispresent in the composite in the form of the corresponding oxide.
 16. Aprocess as defined in claim 1 wherein the composite contains, on anelemental basis, about 0.05 to about 1 wt.% platinum, about 0.1 to about2.5 wt.% nickel, about 0.05 to about 2 wt.% lanthanide series metal, andabout 0.5 to about 1.5 wt.% halogen.
 17. A process as defined in claim 1wherein the catalytic composite is in a sulfur-free state.
 18. A processas defined in claim 1 wherein the contacting of the hydrocarbon with thecatalytic composite is performed in the presence of hydrogen.
 19. Aprocess as defined in claim 1 wherein the type of hydrocarbon conversionis catalytic reforming of a gasoline fraction to produce a high octanereformate, wherein the hydrocarbon is contained in the gasolinefraction, wherein the contacting is performed in the presence ofhydrogen, and wherein the hydrocarbon conversion conditions arereforming conditions.
 20. A process as defined in claim 19 wherein thereforming conditions include a temperature of about 800° to about 1100°F., a pressure of about 0 to about 1000 psig., a liquid hourly spacevelocity of about 0.1 to about 10 hr.⁻¹, and a mole ratio of hydrogen tohydrocarbon of about 1:1 to about 20:1.
 21. A process as defined inclaim 19 wherein the contacting is performed in a substantiallywater-free environment.
 22. A process as defined in claim 19 wherein thereforming conditions include a pressure of about 100 to about 450 psig.23. A process as defined in claim 19 wherein the contacting is performedin a substantially sulfur-free environment.
 24. A process as defined inclaim 16 wherein the type of hydrocarbon conversion is catalyticreforming of a gasoline fraction to produce a high octane reformate,wherein the hydrocarbon is contained in the gasoline fraction, whereinthe contacting is performed in the presence of hydrogen, and wherein thehydrocarbon conversion conditions are reforming conditions.